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Biophysical evaluation of aminoclay as an effective protectant for protein stabilization during freeze-drying and storage

Authors Song JG, Lee SH, Han HK

Received 19 September 2016

Accepted for publication 12 November 2016

Published 12 December 2016 Volume 2016:11 Pages 6609—6619


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Thomas Webster

Jae Geun Song, Sang Hoon Lee, Hyo-Kyung Han

College of Pharmacy, Dongguk University, Goyang, South Korea

Abstract: This study aimed to evaluate aminoclay (3-aminopropyl-functionalized magnesium phyllosilicate) as an effective protectant for the stabilization of protein formulation in freeze-drying. Bovine serum albumin (BSA), as a model protein, was freeze-dried with aminoclay at various concentrations, and the effects of aminoclay on the structural stability of proteins were compared with those of the conventional stabilizers. The structural characteristics of the protein were determined by size exclusion chromatography (SEC), circular dichroism (CD), and Fourier transform infrared (FTIR) spectroscopy. Furthermore, physicochemical and morphological characteristics were examined by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). XRPD and DSC patterns indicated that the glass transition temperature (Tg) of the amorphous formulation of aminoclay mixed with proteins was gradually elevated as the concentration of aminoclay increased. FTIR and CD spectral analysis suggested that the protein structure was well maintained with aminoclay during the freeze-drying process and 3 months of storage at 4°C and 40°C. Furthermore, aminoclay conferred the greatest protection against aggregation and retained the monomer content of BSA even at a high temperature. The morphological characteristics of lyophilized proteins were also well conserved during the storage with aminoclay. These results suggested that aminoclay may be useful as an alternative stabilizer for maintaining the structural stability of protein formulations.

Keywords: aminoclay, cryoprotectant, lyoprotectant, freeze-drying, protein, stability

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